The close escort was supported by six Home Fleet destroyers led by HMS Onslow (Captain Robert Sherbrooke).

Convoy JW 51B was opposed by four U-boats in a patrol line in the Norwegian Sea and the aircraft of Luftflotte 5 based in Norway.

A surface force comprising the heavy cruisers Admiral Hipper, Lützow and the destroyers Z16 Friedrich Eckoldt, Z4 Richard Beitzen, Z6 Theodor Riedel, Z29, Z30, Z31 was stationed at Altenfjord.

Three of the ships rejoined on 30 December, but Chester Valley, in company with the armed trawler Vizalma, and another, with the destroyer Oribi, remained separated.

On 31 December the German ships, in two sections, met the ocean escort of Convoy JW 51B, and after a sharp engagement, which left the minesweeper Bramble and the destroyer Achates sinking and Onslow, damaged; the attacking force was driven off.